There are a number of plug type container closure systems in use today. Most are manufactured with the container and are designed to be opened easily, used once, discarded along with the container, and perhaps recycled. Some other considerations often mentioned for this type of "flip top" closure system are: a desire to provide a secure yet easily opened seal, to ensure that contents are accessible but not accidentally so; a desire to keep the plug member attached to the container after the container is opened, to prevent littering; and a desire to keep all exposed edges rounded, to prevent cuts.
Some closure systems are designed to be resealable, such as U.S. Pat. No. 4,232,797 which provides a plastic plug thermoformed to overlap the inner and outer surfaces of a container wall to seal an opening therein. After removing the plug from the container opening, the plug can be snapped back into place, which should serve to reseal the container opening. The quality of this seal and whether it can be repeatedly achieved is open to question.